The Transcriptional Response of Yeast to Saline Stress

Abstract

Adaptation to changes in extracellular salinity is a critical event for cell survival. Genome-wide DNA chip analysis has been used to analyze the transcriptional response of yeast cells to saline stress. About 7% of the genes encoded in the yeast genome are induced more than 5-fold after a mild and brief saline shock (0.4 M NaCl, 10 min). Interestingly, most responsive genes showed a very transient expression pattern, as mRNA levels dramatically declined after 20 min in the presence of stress. A quite similar set of genes increased expression in cells subjected to higher saline concentrations (0.8 M NaCl), although in this case the response was delayed. Therefore, our data show that cells respond to saline stress by inducing the expression of a very large number of genes and suggest that stress adaptation requires regulation of many cellular aspects. The transcriptional induction of most genes that are strongly responsive to salt stress was highly or fully dependent on the presence of the stress-activated mitogen-activated protein kinase Hog1, indicating that the Hog1-mediated signaling pathway plays a key role in global gene regulation under saline stress conditions.

Genome-wide location and regulated recruitment of the RSC nucleosome-remodeling complex

“…These genes are repressed when cells are grown in rich glucose-containing medium, but are strongly induced upon depletion of a fermentable carbon source or in response to other unfavorable environmental conditions (DeRisi et al 1997; Holstege et al 1998;Posas et al 2000;Alexandre et al 2001;Causton et al 2001). By analogy with Hir-dependent repression of HTA1/HTB1, we imagined that RSC might be associated with the transcriptionally repressed state of genes involved in carbohydrate metabolism.…”

Microarrays for microbiologists

“…Changes in gene expression can be very transient. A 10 min exposure of yeast to 0n4 M NaCl resulted in the induction of 1300 genes, whereas only 172 induced genes were detected after 20 min (Posas et al, 2000). Learning to use microarrays often takes months rather than weeks, and requires the supportof an experienced laboratory.…”

MAP kinases as structural adaptors and enzymatic activators in transcription complexes

“…Genome-wide transcript profiling shows that Hog1p controls expression of~600 genes in response to osmostress (O'Rourke and Herskowitz, 2003;Posas et al, 2000;Rep et al, 2000). It regulates several transcription factors, each responsible for controlling expression of a subset of osmoresponsive genes.…”